Power Play

Our eBay Motors Editors Charity Challenge Cobra gets a tune-up

Horse Sense: eBay Motors is the world's largest online used car marketplace. Since its launch in April '02, eBay Motors has grown to the point that it now features 1.4 million new and used parts available on the site each month. An automotive part or accessory is sold every two seconds with over 600,000 parts and accessories are available for sale each day.

Throwing parts and money at a vehicle doesn't mean it's going to go fast. Our mission was the find the right combination of parts to win the eBay Editors' Challenge. We already had a nice car. Now we had to get it up to speed to get ready for our showdown.

Our challenge was to find a Mustang and then modify it as part of a competition with other Primedia automotive magazines in a winner-take-all affair. The battle would take place on the road course and drag strip at Fontana Raceway in California. Each team was given a budget of $25,000. The vehicle and the majority of the parts would have to be purchased on eBay Motors while the progress of each team would be posted for readers to follow on www.editorscharitychallenge.com. Teams were allowed just a handful of sponsors with a maximum contribution of no more $500 each. Once the challenge was complete, the cars would be displayed and then auctioned off with the proceeds going to Charity Cars, Inc.

The teams were split up as follows: 5.0 Mustang would anchor Team Mustang with Popular Hot Rodding, Car Craft and Muscle Mustangs & Fast Fords providing a vast wealth of experience and knowledge. The other teams would go to war with real winners like a 1997 Chevy standard-cab pickup, 1994 Acura Integra, a VW Golf, BMW M3, Dodge 2500 pickup and an early model Nova. Things got weird after that as another team actually got a nostalgia front-engine dragster. Can't wait to see that on a road course!

Choosing the Right 'Stang
We knew that selecting our weapon of choice would be crucial to our success. With nearly 2.6 million Fox-body Mustangs produced between 1979 and 1993, there was no doubt this car would have a ton of high-performance and restoration parts on eBay Motors. The fuel injected '87-'93 models have always been the most desirable and, with just over a million made during that time span, we felt pretty comfortable about having a good selection to choose from. Aside from the limited-production Cobra R (just 107 made), the 1993 Cobra represented the high water mark for these cars. We felt fortunate to find a really nice car with just 13,000 miles in short order. It already had a lot of the right parts with a Cartech turbo kit with a Precision PT-44 turbo that will support up to 540 hp. The supporting cast was made up of a four-point roll bar, Kenny Brown matrix subframes, upper/lower control arms made for a nice starting point. Yet the car had issues. An emissions-legal, quarter mile best of 13.57 at 103.99 mph indicated us there was certainly more left in the car. Constant backfiring, sputtering and cutting off on deceleration told us that improving out tuneup was the place to start.

Doing a search under "Engine Management" on eBay Motors led us to some possibilities, but we settled on the new Big Stuff 3 SEFI engine management system after talking to tuning guru John Meaney. We discovered that this is the only sequential system on the market to include a Wide Band O2 air/fuel ratio control along with individual cylinder fuel and spark compensation as standard features. A little bit of pleading and arm twisting resulted in both Precision Turbo and John came aboard, so we bid on and won our Big Stuff 3 (BS3) system and the fun began.

EMS Basics
Why go for an aftermarket engine management system? The answer is because your car's stock ECU is set up more for drivability, emissions and fuel mileage rather than all-out performance. Some do this by reinventing the wheel with a complete, standalone ECU, while others go for smaller, less-expensive units that will piggyback and work in conjunction with the calibrations in the stock ECU system. Going with the standalone unit offered us a bit more flexibility in tuning. Some of the issues that have to be addressed with any modified engine are idle quality; part- and full-throttle spark timing and fuel-delivery calibrations. In the case of our eBay project car, having a turbo also meant that we had to carefully manage fuel enrichment and timing retard as it related to boost in order to get max power without hurting the engine.

BS3 gave us a lot of tools to work with. Besides the wideband O2 air/fuel ratio control along with individual cylinder fuel and spark compensation, other standard features included configurable load and rpm axis, programmable “peak-and-hold” injector drivers and vastly improved transient fueling and speed-density algorithms. Options include full internal datalogging capability and an interface with Racepak's UltraDash for high-end race applications. In this case, we found the Ford-style Idle Air Control, .9V to 4.5V throttle sensor position voltage capability and seamless decel fuel cutoff to be particularly appealing for our 5.0 EEC-IV application.

The key with any engine management system, however, is to realize that such a system cannot improve a vehicle's performance by itself. What it does do is give the tuner a means of changing the ECU's base map calibration for improved performance. Getting it right requires some experimentation, but going too far one way or another in the wrong can also result in a blown engine. That's why smart users employ the use of a proven tuner or make only small, incremental changes as they gain experience.

First Things First
For any engine modification to work to its full potential, you must first be certain that your engine is in good operating condition. Making sure you have a good battery with solid connections, enough coolant in the radiator and having clean, properly sized fuel injectors are typical of some of the things that should be checked.

We also took the time to take our Team Mustang entry during a local test an tune night to baseline on our performance. We made about a dozen runs with two different drivers and came up with a best e.t. of 13.57 seconds at over 103 mph. While we were running just 5 pounds of boost through full emissions, we knew that there had to be more. Big Stuff 3 proved to be just the tool we needed.

Spending an evening or two to thoroughly familiarize ourselves with the installation manual made the process easier than we thought it would be. To improve the overall wiring harness installation process, the wiring harness was manufactured with identification labels at the end of each wire or connector to ensure that connections were terminated correctly. The best location for the firewall hole that we fed the harness through was close to the center of the vehicle so we had plenty of length to connect to all the sensors on our engine. Once all of the hardware was installed, the next step was to load the BigComm software into our laptop computer and then connect it to the BS3 ECM. With the key turned to the Accessory position (without starting the engine), we looked to see if all of the electronics could talk with each other. Verifying that you are getting data from all of the sensors and checking to see if the readouts were within expected ranges for the conditions at hand told us we were ready to start the engine.

Our BS3 was delivered with a basic calibration that matched our engine configuration so the engine could start and run—and it started with the first turn of the switch. Users also have the option of entering their own data about the engine setup so the software can automatically construct a basic fuel and spark curve. Taking the time to establish that information correctly rather than guessing at it makes a big difference in getting to where you want to go with your tuneup.

Understanding The Software
Assuming that any shop that bolts parts on a car can also tune a car electronically is a big mistake. It's almost always easier to bolt the parts in place than it is to get them to work together at their maximum potential and, at the same time, not damage the engine. Basic computer skills are necessary along with a thorough understanding of tuning and the dynamics of modern engine controls.

In basic terms, the BigComm software is really nothing more than an interface between the BS3 and the engine in your vehicle. It reacts to what strategically placed sensors on the engine and drivetrain tells it and responds based on the parameters established with the tables or algorithms contained in the programmable software. With our Mustang's stock ECU, some of the sensors used included a heated exhaust gas oxygen, manifold absolute pressure, barometric absolute pressure, engine coolant, air-charge temperature, and throttle position.

There are also a number of optional sensors and actuators that are needed to optimize an engine's power potential. To provide meaningful input from the richer air/fuel mixtures used for maximum power, a wideband O2 sensor is often used in order to better control the pulse width of the injector. Peak and hold injector drivers are needed to activate and control high-flow, low-impedance fuel injectors, which are required in high-horsepower applications. Datalogging requires even more components.

Once the BigComm software has been successfully installed, communication with the ECU has been established and the hardware and operating parameters have been configured, users can then begin to manipulate the Air/Fuel Ratio, O2 Correction and Fuel tables. Fine tuning the engine for maximum power and drivability is a repeated process using these tables. That process involves configuring, in order, the air/fuel ratio table for different engine speed and load combinations, the positive and negative O2 correction tables and then the volumetric efficiency values in the Fuel Table.

Advanced tuners can even overcome inefficiencies in the intake manifold design by adjusting the amount of fuel (positive and negative) for each individual cylinder. BS3 can also be configured to help with boost control and even "learn" to a limited extent in order to minimize the amount of O2 correction required to achieve the user defined values in the air/fuel ratio table.

Once the BS3 system was installed, there were few, if any, visible clues that our pony was now answering to a higher authority. Drivability was improved dramatically. While testing at the strip wasn't complete at this writing, readers can check the progress of our project car at www.editorscharitychallenge.com. For a car running full emissions equipment at just 5 pounds of boost, we felt that was a power play that was well worth the time and effort.